Form...

Primary Solids: primary solids are created by the rotation or elongation of primary shapes.  This creates a three-dimensional form with volume and visual weight.  For example, a rectangle can be rotated around itself to create a cylinder with height, width and depth.

Additive Form: The addition of one or more forms to the original form.  Each form can be the same size or varying sizes from other forms.  For example, interlocking volumes are forms that have penetrated each other's space.

Grid Forms: This occurs when forms are placed in a grid-like pattern, equally and orderly spaced from one another.  They appear to be within a grid.  

Rotated Grid: Falls under the Formal Collision of Geometry field.  Occurs when identical forms differing in orientation compete for visual dominance in a space.  A form can be completely enveloped in the other, interlocking, can share share spaces to create a new identity or even be separated but linked by a third element. 

Surface Articulation:  Fall under Formal Collision of Geometry.  Occurs when shape, texture, color and scale of a surface influence the way one perceives the form.